XVI International Botanical Congess

Associations of planktonic, benthic, and oceanic dinoflagellates in coral reef-mangrove ecosystem Pelican Cays, Belize were examined. 72 samples were taken from six sites: Cat Cay, Douglas Cay, Elbow Cay, Lagoon Cay, Fisherman's Cay and Manatee Cay in May 1994-1996. I report on the population of dinoflagellate taxa. Armored species comprised up to 95%of total cell populations in the 20 um size fraction. A total of 110 species in 33 genera were identified, 80 photosynthetic, 30 heterotro nium divergens. Dominant were: 16 Protoperidinium, 11 Gonyaulax and 10 Ceratium species. Toxins producing species present were: 6 planktonic and 16 benthic species. Bloom forming we re: Ceratium furca and Gonyaulax polygramma.This study illutrates the richnes of dinoflagellate assemblages in the Pelican Cays. It establishes dinoflagellates as important component in the microscopic mangrove food web.